Epidemiologists tried to investigate the role of factor Y in the exposure-disease relationship.They developed three tables to show the exposure-disease relationship based on the status of factor Y.Based on the information given,what is the role of factor Y in the exposure-disease relationship? Overall
$\begin{array}{|l|l|l}
& \text { Case } & \text { Control } \
\hline \text { Exposed } & 1,000 & 500 \
\hline \text { Unexposed } & 200 & 500
\end{array}$
Factor Y present
$\begin{array}{|l|l|l}
& \text { Case } & \text { Control } \
\hline \text { Exposed } & 800 & 250 \
\hline \text { Unexposed } & 100 & 250
\end{array}$
Factor Y absent
$\begin{array}{|l|l|l}
& \text { Case } & \text { Control } \
\hline \text { Exposed } & 200 & 250 \
\hline \text { Unexposed } & 100 & 250
\end{array}$

A) Factor Y is a confounder.
B) Factor Y is an effect measure modifier.
C) Factor Y is a mediator.
D) Factor Y is an outcome.
E) Factor Y does not have any role in the exposure-disease relationship.

Question

Epidemiologists tried to investigate the role of factor Y in the exposure-disease relationship.They developed three tables to show the exposure-disease relationship based on the status of factor Y.Based on the information given,what is the role of factor Y in the exposure-disease relationship? Overall
$\begin{array}{|l|l|l} 
& \text { Case } & \text { Control } \
\hline \text { Exposed } & 1,000 & 500 \
\hline \text { Unexposed } & 200 & 500
\end{array}$
 Factor Y present
$\begin{array}{|l|l|l} 
& \text { Case } & \text { Control } \
\hline \text { Exposed } & 800 & 250 \
\hline \text { Unexposed } & 100 & 250
\end{array}$
 Factor Y absent
$\begin{array}{|l|l|l} 
& \text { Case } & \text { Control } \
\hline \text { Exposed } & 200 & 250 \
\hline \text { Unexposed } & 100 & 250
\end{array}$

A) Factor Y is a confounder.
B) Factor Y is an effect measure modifier.
C) Factor Y is a mediator.
D) Factor Y is an outcome.
E) Factor Y does not have any role in the exposure-disease relationship.

Quizplus · Accepted Answer

In the overall table,the odds ratio equals the odds of exposure among the cases (1,000/200) divided by the odds of exposure among the controls (500/500).The ratio in overall equals 5.In the table when Y is present,the odds ratio equals the odds of exposure among the cases (800/100) divided by the odds of exposure among the controls (250/250).This ratio in overall equals 8.In the table when Y is absent,the odds ratio equals the odds of exposure among the cases (200/100) divided by the odds of exposure among the controls (250/250).This ratio in overall equals 2.The odds ratios of exposure vary by the presence of factor Y,and the overall odds ratio is also different from stratified odds ratios.This association indicates that factor Y is an effect measure modifier which changes the effect of exposure to the outcome by its status.

Epidemiologists Tried to Investigate the Role of Factor Y in the Exposure-Disease